Process of treating asphalt



UNITED STATES ATENI l l lfiht IVALTER S. IVILKINSON, OF BALTIMORE, MARYLAND.

PRCCESS OF TREATING ASPHALT.

SPECIFICATION forming part of Letters Patent No. 597,892, dated January 25, 1898.

Application file-d December 8, 1897. Serial No. 661,172. (No specimens.) Patented in England March 1, 1897, No. 5,439; in Belgium March 8, 1897,110. 126,712; in Italy March 6, 1897,110. 86,202; in Cape of Good Hope March 25, 18975110. 1,315; in Austria June 6,1897,N0.47/2,139; in France June 8, 1897.110. 264,576, andin Hungary July 7,1897,l l0. 8,935. 7

To and whom it may concern.-

Be it kn own that I, WALTER S. WILKINSON, a citizen of the United States, residing in the city of Baltimore and State of Maryland, have invented a new and useful Process of Treating Asphalt, (for which I have obtained the following Letters Patent: in Great Britain, No. 5, 139, March 1, 1897; in Belgium, No. 126,712, March 3, 1897; in Italy, No. 86,202, March 6, 1897; in Cape of Good Hope, No. 1,315, March 25, 1897; in France, No. 264,576, June 8, 1897; in Austria, No. 47/2,139, June 6, 1597, and in Hungary, No. 8,935, July 7, 1897,) of which the followin gis a specification.

It is known to those who have had experience in preparing asphalt for use in paving in the Uni ted States, that some asphalts, other conditions being equal, disintegrate much more rapidly when they are wet than when they are dry.

Various causes for this evil have from time to time been assigned :Some have said that 'it was due to the presence of the residuum of petroleum used to temper or flux the asphalt of the pavement;-others that it was owing to the use of malt-ha or asphaltic oil, which is more volatile than good residuum of petroleum ;and still others that it was occasioned by the non-bituminous organic matter contained in the asphalt.

I have discovered and demonstrated that the soluble salts and non-bitu minous organic matter contained in the asphalts which thus disintegrate, constitute very destructive elements of such portions of asphalt pavements as are subjected to water, as opposed to those portions which are for the main part dry, and that the dissolving of the soluble salts and the soluble non-bituminous organic matter, together with the incidental removal of some insoluble non bituminous organic matter, breaks up the structure of the asphalt and causes the disintegration and destruction of the pavement.

The soluble salts which I have found in the kinds of asphalt which are so affected by water, consist principally of sodium chlorid,

and sodium sulfate, with small quantities of potassium,calcium,and magnesium, sulfates, and ammonium chlorid.

I have found that when what is known as dried or refined asphalt, which has been produced from a crude asphalt containing appreciable percentages of soluble salts and nonbituminous organic matter,(which are not eliminated .in the process of drying or socalled refining, and are, therefore, found in an increased percentage to the whole in the dried or refined product,)is for some hours immersed in water, it will begin to exhibit disintegration and the formation of a scum or detritus upon its surface, and that this disintegration will continue for some hours to an apparently constantly increasing extent, but that in the course of a few days at most it will nearly if not quite cease.

I have further found that if this soft detritus be gently scraped off with a dull-edged instrument, and'the refined or dried asphalt be then replaced in water, the same action will immediately begin, and that, after further immersion for a corresponding period, an equal quantity of detritus will be formed,.- and further that if the operation be repeated sufficiently often, the entire mass of the original piece of asphalt will be disintegrated and changed into the form which I have termed scum or detritus.

This scum or detritus has hitherto been regarded as decayed or destroyed asphalt, Worthless for useful purposes.

I have, moreover, found that the asphalt is not only not in the slightest degree injured by this breaking up of its structure, but that upon the contrary its worst, if not its only, detrimental elements are removed from it by the action of the water,and that if the detritus be melted, the resulting agglomerate will be a better and more refined asphalt than. that from which it itself was derived.

In proof of this assertion it is only necessary to place a piece of the re-melted detritus in water, and it will be found that it is not only not affected at all, but that its surface will for an indefinite period remain bright and clean.

Analysis of the Water in which the refined or dried asphalt has been disintegrated, has demonstrated that it contains a considerable percentage of soluble salts, and some organic matter, partly in suspension and partly in solution ;and it has also been found that a saturated solution of salt water has no effect upon asphalt, either crude or refined, placed in it.

The obvious deduction from these results has been that the solution of the soluble salts and non-bituminous organic matter by the water occasions the disintegration of the surface of the asphalt and the formation of the detritus.

Pursuing the experiment, I have immersed in Water a piece of crude asphalt, and found that the disintegration is more rapid than in the case of refined asphalt, and that a few hours immersion is sufficient to occasion the formation of a very considerable amount of detritus.

Pursuing the experiment further yet, Ihave removed the first detritus, re-immersed the crude asphalt, and repeated the operation of removal, until a quantity of detritus sufficient to handle and melt has been obtained.

This material having been melted and cooled and then placed in water, I have found that there was no action of any kind upon it, and that it, in fact, was a better refined asphalt than could ordinarily be produced from a crude asphalt containing an equal percentage of soluble salts and non-bituminous organic matter.

Vhen asphalt so prepared and mixed with a proper proportion-of a proper flux, such, for instance, as the residuum of petroleum, and thereby agglomerated into what is known in the art as asphaltic paving cement, is used in the manufacture of sheet and block pavements, it is much more durable than any cement heretofore produced from crude asphalt containing any considerable percentage of soluble salts, and possesses a higher cementing power than asphalt not so treated.

My process of desalifying and removing non-bituminous organic matter from asphalt, as above described,and which, as a general statement, may be said to comprehend the bringing of the component particles of the asphalt into contact with a sufficient quantity of water to dissolve out of and eliminate that it may contain,--the dissolving of a large portion of the soluble non-bituminous organic matter,-and the removing of other non-bituminous organic matter which is in- I soluble,may be effectuated by the following operation, namely:-first :by comminuting the asphalt, either by maceration in cold water or water'of ordinary temperature, or by disintegration mechanically; and, second:by agitating the macerated or disintegrated comminuted product in water by suitable means;-with the result that the soluble salts and soluble non-bituminous organic matter are dissolved and eliminated, and the suspended insoluble non-bituminous organic matter removed. I

The means for effecting disintegration are not material, but a device known as the Denmead disintegrator answers the purpose cheaply and rapidly.

Any preferred means may be employed to effect the agitation of the aforesaid second step,which may obviously be repeated as often as is found necessary to dissolve and practically eliminate all the soluble salts, and also to remove a large portion of the soluble non-bituminous organic matter and a portion of the insoluble non-bituminous organic matter,the greater the amount of water in pro portion to the amount of asphalt used at any one operation, the less frequently it becom ing necessary to repeat the operation.

After the desalification and elimination of soluble and insoluble non-bituminous organic matter has been completed and the water drained OK, the asphalt may be agglomerated, that is to say, dried melted or refined by any of the usual methods.

Having thus described my invention, I claim and desire to secure by Letters Patent 1. The process of desalifying and removing non-bituminous organic matter from asphalt,

which consists, first, in comminuting it, and, second, in agitating the comminuted product in water, substantially as and for the purposes set forth.

2. The process of treating asphalt, which consists, first, in comminuting it and agitating the comminuted product in water, for the purpose of desalifying it and removing from it non-bituminous organic matter, and, sec- 0nd, in agglomerating the resultant material,

substantially as and for the purposes set forth. from it all or nearly all of the soluble salts 3 5 myinvention I have hereunto sign ed my name this 4th day of December, A. D. 1897.

In testimony that I claim the foregoing as WALTER S. WILKINSON. In the presence of-- OLIVE L. MAoALEsTER, CHARLES MACALESTER. 

